All 3 cats were extremely hesitant at first. A 5 second peek through the hole was the most they’d give it. I’m glad I left the old boxes out because they wouldn’t use this one for over a week.  I knew they’d appreciate it once they understood it, so I opened the front up all the way, which allowed them to get a full view of what’s inside and walk right in. Left it like that for a few days, then closed it back up. They went in through the hole no problem after that. 
This thing is adorable. Easy to clean. Keeps the area clean. I’m buying 2 more.